NEW YORK (AP) - Activist investor Carl Icahn is increasing his stake in Chesapeake Energy, a company where he has already pushed for sweeping changes in governance.

Company shares rose 2.3 percent Tuesday before the opening bell.

A regulatory filing shows Icahn now owns 8.98 percent, compared with a 7.6 percent stake in the Oklahoma City company he held this summer. Icahn first invested in Chesapeake Energy Corp. in May.

Since then, he's pushed for a slew of changes including the stripping of CEO Aubrey McClendon's chairman title. Icahn also shook up the company board. In June, Chesapeake Energy Corp. appointed four new directors that were hand-picked by the company's largest investors.